With increasing awareness of information security, biometrics are being introduced for authentication for unlocking of and login in personal information terminals, such as smartphones, slate terminals, and tablet terminals.
When a living body is imaged with an information terminal, if the position or posture of a part of the living body that is a subject is not proper, a disadvantage that it would not be possible to correctly extract biological information used for authentication or the extracted amount of characteristics would not match the registered amount of characteristics may occur. In such a case, the time for authentication extends and furthermore the accuracy of authentication lowers.
As an exemplary technology to deal with the problem, there is a technology for displaying an operation instruction for positioning and guiding a part of a living body such that the operation instruction is superimposed onto an image of the living body that is acquired by a sensor.
Patent Document 1: Japanese National Publication of International Patent Application No. 2010-541046
Patent Document 2: Japanese Laid-open Patent Publication No. 2007-052534
Patent Document 3: Japanese Laid-open Patent Publication No. 2009-157908
Patent Document 4: Japanese Laid-open Patent Publication No. 2004-258714
Patent Document 5: Japanese Laid-open Patent Publication No. 2008-071030
The above-described technology, however, has a limit to improvement of accuracy of authentication as described below.
For example, from among information terminals, such as smartphones, slate terminals, and tablet terminals, there are terminals in each of which a sensor that images a living body is disposed on the back surface, i.e., on the back of the screen. When such an information terminal images a living body, because it is not possible for a user to directly view the position of the sensor, it is more difficult to dispose a part of the living body in an appropriate location. In each of the above-described technologies, however, an operation instruction for positioning or guiding the part of the living body is only issued on an assumption that the sensor is set in a position that the user can directly view and thus it is not possible to apply such positioning and guiding to a case where the sensor is on the back surface. For this reason, it is not possible, with the above-described technologies, to solve the disadvantage that biological information used for authentication is not necessarily extracted or the amount of extracted characteristics does not necessarily match the registered amount of characteristics, which may lower the accuracy of authentication.